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Optimal
Task Allocation and Distributed Sensing in Collective Autonomous Robotics
William
Agassounon, Alcherio
Martinoli, Rodney
Goodman
Our research
aims at studying two particular topics within the Collective Robotics
field, these are the division of labor and the dynamic task allocation.
The Swarm Intelligence approach can be applied to fully distributed
systems that consist of several autonomous decision making entities
working together with minimal communication and local perception to
complete one or several tasks. Our approach is inspired by biological
systems such as colonies of social insects (ants, bees, termites, etc)
in which the collective behavior often emerges from a series of local
agent-to-agent and agent-to-environment interactions. We are developing
response threshold-based algorithms for optimal task allocation and
probabilistic models that provide accurate forecast of the resulting
collective behavior. Finally, one of the main strengths of this project
is the attempt to create a theoretical framework for real embedded systems
provided with threshold allocation mechanisms. These systems are therefore
analyzed at several implementation levels, from analytical probabilistic
models to real robots experiments through embodied sensor-based simulators.
(full report)
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Awareness-Based
Computation
George Barbastathis, Greg
Billock, Demetri Psaltis,
Christof Koch
In this
project, we are developing design principles for intelligent systems
that can interact with very complex, variable, and poorly modeled environments.
In doing so, we draw inspiration from the discoveries of neurobiology
relating to the role of attention and awareness. These aspects of biological
processing systems is key in conferring on them the ability to function
in such high-dimensional real-world environments. At the heart of our
architecture lies the idea of adapting an abstraction of awareness with
which to endow artificial man-made systems. (full
report)
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Configurable
Architectures and Systems for Real-Time Low-level Vision
Arrigo Benedetti,
Pietro Perona
The long-term
goal of this project is to build an infrastructure for the design and
implementation of real-time computer vision systems. Since vision algorithms
are compute-bound we have chosen the technology of Field Programmable
Gate Array (FPGAs), that allow to exploit the parallelism inherent to
the first stages of low-level vision tasks. The first problem that we
have considered is the real-time computation of the optical flow measured
from the sequence of images captured by a video camera. We have designed,
built and demonstrated a system able to select in real-time 2-D visual
features on a commercially available platform. During this process we
have learned that the system level architectures of commercially available
configurable systems are not optimized for low level vision tasks, therefore,
we have designed a novel architecture dedicated to real-time processing
of video streams. A system based on this architecture has been built
and is currently being tested. More recently, we have studied the problem
of bit-width computation for the optimization of the data paths found
in digital video signal processors. (full
report)
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Awareness-Based
Computation: The Bin Packing Problem
Greg Billock,
Demetri Psaltis, Christof
Koch
In previous
work (see report entitled Awareness-Based Computation),
we have investigated the impact of using approaches to simulated environments/problems
inspired by the way human beings use awareness and attentional mechanisms
to interact with a complex world. In this work, we explore how this
works in the context of a familiar computer science problem: bin packing.
As an abstract problem, the bin-packing problem has the advantage of
having been subjected to extensive analysis and so much is known about
it. It is a very important practical problem, as well, with applications
to cutting stock, machine and job scheduling, parallel processing scheduling,
FPGA layout, loading problems, and more. By using ideas about reduced
representations of what is most important in an on-line solution of
the problem, we are able to devise a heuristic which outperforms existing
heuristics, and understand how and why it does so. (full
report)
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3D Photography
on Your Desk
Jean-Yves Bouguet, Pietro
Perona
We are
developing a simple and inexpensive method for extracting the three-dimensional
shape of objects by using weak-structured lighting. Experimental results
demonstrate that the error in reconstructing the surface is less than
1%. (full report)
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Evolving
Robust, Collective Patrolling Behavior Using Genetic Algorithms
Joseph Chen, Alcherio
Martinoli,
Rodney
M. Goodman
Evolution
is a powerful force. Harvester ants have successfully evolved to efficiently
patrol their territory for different type of events (food items, enemy
intrusion, etc.). The goal of this project is to study how effective
and robust patrolling behavior can be evolved first in embodied, sensor-based
simulations and then in real robot experiments. We will use evolutionary
techniques (Genetic Algorithms, GA) for exploring the individual control
parameters that play a crucial role in the team patrolling performance.
In order to better understand the required individual and group capabilties
for effective patrolling, we will test the influence of individual navigation
capabilities and different fitness functions. We will also note whether
any interesting collective behavior develops if the robots are allowed
to directly communicate at each encounter, without introducing any type
of stigmergic mechanism (e.g. pheromones). (full
report)
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Distributed
Collective Building of Two-Dimensional Structures Using Autonomous Robots
Kjerstin Easton, Alcherio
Martinoli, Rodney
Goodman
Using
autonomous robots to build three-dimensional structures is a distant
goal, but the first step in approaching collective building is to construct
two-dimensional architectures. Using a team of miniature Khepera robots
with manipulation and vision capabilities, we will implement a building
technique modeled after qualitative stigmergic construction mechanisms
used by social insects. This technique will allow the robots to communicate
building instructions through modifications to the local environment,
avoiding dependence on explicit robot-to-robot communication and lending
itself to implementation with any number of robots. (full
report)
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Distributed
Turbulent Flow Control by Neural-Networked MEMS
Zhigang Han, Qiao
Lin, Xuan-Qi Wang, Fukang
Jiang, Thomas Tsao, Yu-Chong
Tai
Collaborators: Vincent Koosh (Caltech), Rodney Goodman (Caltech), James
Lew (MAE, UCLA) , Chih-Ming Ho (MAE, UCLA)
The ultimate
goal of this project is to develop fully integrated MEMS with microsensors,
microactuators, and microelectronics (M3) for turbulent boundary
layer control. We have developed many generations of MEMS shear-stress
sensors for vortex detection. The latest one is a fully integrated shear-stress
sensor using a post-IC process that is added onto foundry-processed
CMOS wafers. This shear-stress sensor uses a gate-polysilicon hot-wire
as the sensing element that sits on a freestanding Parylene diaphragm
suspended over a cavity. A special Parylene vacuum sealing and etch
back process is used to achieve better thermal isolation and overall
sensitivity. Wind tunnel testing of this sensor shows a sensitivity
of 30 mV/Pa and a measured bandwidth of 18 kHz. We have also performed
extensive theoretical analysis of these sensors. The resulting 2D MEMS
shear-stress sensor theory, which includes heat transfer effects ignored
by the classical theory, is verified by experimental data. We also perform
3-D heat transfer simulation and the results agree with the testing
data and support the proposed new theory. (full
report)
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Guiding
a Robot with an Analog VLSI Motion Sensor Based on the Visual System of
the Fly
Reid Harrison, Christof Koch
Sensing
visual motion gives a creature valuable information about its interactions
with the environment. Flies in particular use visual motion information
to navigate through turbulent air, avoid obstacles, and land safely.
Mobile robots are ideal candidates for using this sensory modality to
enhance their performance, but so far have been limited by the computational
expense of processing video. Also, the complex structure of natural
visual scenes poses an algorithmic challenge for extracting useful information
in a robust manner. We address both issues by creating a small, low-power
visual sensor with integrated analog parallel processing to extract
motion in real-time. Because our architecture is based on biological
motion detectors, we gain the advantages of this highly evolved system:
a design that robustly and continuously extracts relevant information
from its visual environment. We show that this sensor is suitable for
use in the real world, and demonstrate its ability to compensate for
an imperfect motor system in the control of an autonomous robot. The
sensor attenuates open-loop rotation by a factor of 31 with less than
1 mW power dissipation. (full
report)
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Distributed
Plume Tracing
Adam
T. Hayes, Alcherio
Martinoli, Owen
Holland, Rodney
M. Goodman
The objective
of this project is to study biologically inspired algorithms which enable
a robot or group of robots to track an odor plume to its source, with
an appropriate combination of speed, efficiency, reliability, and accuracy.
Research is conducted at three levels: non-embodied point simulations,
embodied sensor-based simulations, and real robots. The simulations
use sensors and actuators which are based on the capabilities of the
real robots, and plume information is derived from empirical data files
recorded from real plumes or realistic plume simulators. In simulation
we explore the performance of various families of simple algorithms,
as well as the potential for automated parameter tuning and on-line
learning. We assess the most promising algorithms on real robots, which
are equipped with Caltech olfactory sensors, anemometric devices, and
simple communication systems. (full
report)
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Actuated
Surgical Endoscopes for Minimally Invasive Surgery
Hans D. Hoeg, Joel W. Burdick,
A. B. Slatkin
Our effort
is aimed at developing articulated surgical endoscopes that can access
the interior of the human body in a minimally invasive manner for the
purposes of visualization, diagnosis and therapeutic intervention. We
have specifically focused on design and construction of scopes for use
in brain surgery and gastrointestinal procedures. (full
report)
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Super
Manueverable UAV Controlled by M3 System
Fukang Jiang, Charles Grosjean, Yong Xu, Yu-Chong Tai
Collaborators: Chih-Ming Ho (MAE, UCLA), Ray Morgan, Martyn Cowley, Scott
Newbert (AeroVironment Inc.)
An aircraft
for the future - having no tail, controlled by M3
systems, and with no traditional control surfaces - will be developed
for low altitude surveillance. A new robust system of distributed microsensors
and microactuators, with associated microelectronics (a M3
system) will be designed and fabricated to satisfy flight test requirements.
A new aircraft will be designed from scratch to accentuate the concept
of achieving aerodynamic maneuvering through a micromachine-based deformable
smart surface. This new aircraft design concept can significantly reduce
weight, overall power consumption and radar cross-section. (full
report)
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Psychobiophysics
of Transcranial Magnetic Stimulation
Yukiyasu Kamitani, Shinsuke Shimojo
We investigate
the relationship between human visual experience and underlying neuronal
electrical activity, using transcranial magnetic stimulation (TMS).
We explore methods that make the effect of TMS on the visual cortex
directly visible, to look at purely cortical activity underlying our
conscious visual experience. We also develop a biophysical theory to
simulate the effect of magnetic stimulation on single neurons. Based
on it, we create compartmental models of realistic cortical neurons
to find neural activity underlying perceptual effects of TMS. (full
report)
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VLSI
Implementation of a Neural Network
Vincent Koosh,
Rodney Goodman
We are
developing a single chip solution to implement a feedforward neural
network and training algorithm. (full
report)
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Neural
Coding of Electric Field Amplitude Modulations in Eigenmannia Electric
Fish
Gabriel Kreiman, Ruediger Krahe (Department of Biology, U.C. Riverside),
Fabrizio Gabbiani, Walter Metzner (Department of Biology, U.C. Riverside),
Christof Koch
We are
using the electric fish as a model to study the encoding of time-varying
signals by single and multiple neurons. Our approach combines signal
detection and information-theoretic ideas to quantify the amount of
information conveyed by sensory afferents and its targets about amplitude
modulations in the electric field. We have shown that single sensory
neurons robustly encode a significant proportion of the incoming signal
while the pyramidal cell targets extract specific features of the signal.
We are currently performing a quantitative study of the possibility
of extracting these features by coincidence detection of two pyramidal
cells. (full report)
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Visual
Sensor With Resolution Enhancement by Mechanical Vibrations
Oliver Landolt,
Ania Mitros, Christof
Koch
The resolution
of both biological and man-made vision systems is limited by the finite
spacing between receptors. This limit can be overcome by applying continuous
low-amplitude vibrations to the image or taking advantage of existing
vibrations in the environment. Some animals rely on this principle for
improved visual resolution. We are applying it to a novel CMOS visual
sensor to increase resolution and decrease fixed pattern noise. (full
report)
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Micromachined
Gyroscope Using Operating Principles from the Fly's Halteres
Oliver Landolt,
Zhigang Han, Christof Koch,
Yu-Chong
Tai
We are
developing a surface micromachined 2D angular velocity sensor -- also
known as gyroscope -- with the intention of minimizing power
consumption. By using a detection principle inspired by the fly's haltere
system, we expect our sensor to tolerate a higher noise level than previous
designs for detecting the direction of the axis of rotation, thereby
enabling a significant reduction of supply voltage and power consumption.
Another feature is that the mechanical structure will be fabricated
with a material called parylene using a novel technology developed in-house.
The target application is flight control in extremely small air vehicles.
(full report)
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Holographic
Imaging of Biological Samples
Wenhai Liu, Demetri
Psaltis
We are
developing an imaging system with the ability of imaging a 3D object
plus the color spectrum information. It makes use of the spatial and
wavelength selectivity of volume holograms, which act as multiple lens
and color filters to separate the 2D slices with different color from
the 3D object into various detectors. It will be a powerful tool for
imaging application in cell biology, biochemistry, material research
and any other 3D imaging application. (full
report)
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Support
Vector Machines - A New Approach to Learning
Malik Magdon-Ismail, Jennie
Yoder, Yaser
Abu-Mostafa
Support
Vector Machines are a method of extracting information from few noisy
data points. A classification boundary is created allowing the largest
possible margin of error. The technique is robust and easily implemented.
(full report)
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Sensing
and Control for Robotic Fish Locomotion
Richard Mason, Joel
Burdick
We are
studying issues in fluid mechanics, nonlinear control, and sensing that
are necessary for the development of self-propelled robot fish. (full
report)
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Micromachined
Fluidic Couplers
Ellis Meng, Shuyun
Wu, and Yu-Chong Tai
Several
types of silicon fluidic couplers have been designed, fabricated, and
tested for the purpose of facilitating external connections to MEMS
fluidic devices. By using both bulk micromachining and DRIE techniques,
couplers of various geometries have been produced for use with any standard
MEMS fluidic port. Furthermore, couplers exhibit excellent performance,
having an operating range of at least 0-1300 psi. (full
report)
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Optically
Programmable FPGA Systems
Jose Mumbru, Gan Zhou,
Arrigo Benedetti, Xin An,
George Panotopoulos,
Fai Mok, Demetri Psaltis, Pietro
Perona
Reconfigurable
processors bring a new computational paradigm where the processor modifies
its structure to suit a given application, rather than having to modify
the application to fit the device. The Optically Programmable Gate Array
(OPGA), an enhanced version of a conventional FPGA, utilizes a holographic
memory accessed by an array of VCSELs to program its logic. Combining
spatial and shift multiplexing to store the configuration pages in the
memory, the OPGA module is very compact and has extremely short configuration
time allowing for dynamic reconfiguration. The reconfiguration capability
of the OPGA can be applied to solve more efficiently problems in pattern
recognition and searches in databases. (full
report)
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Visual
Input for Pen-Based Computers
Mario E. Munich,
Pietro Perona
Our work
focuses on the development of a visual interface for pen-based computers.
We are building a system that visually tracks the trajectory of a pen
in real-time and recovers the handwritten strokes with sufficient spatio-temporal
resolution and accuracy to enable handwritten character recognition.
(full report)
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Camera-Based
ID Verification by Signature Tracking
Mario E. Munich,
Pietro Perona
The goal
of this project is to develop a vision-based biometric technique based
on visual capturing of signatures and to evaluate the performance of
the system. (full report)
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Set-Valued
Analysis for Switching Systems
Todd Murphey, Joel
W. Burdick
Conventional
nonholonomic motion planning and control theories do not directly apply
to "overconstrained vehicles,'' such as the Sojourner vehicle of the
Mars Pathfinder mission. This research investigates some basic issues
that are necessary to build a motion planning and control framework
for this potentially important class of mobile robots. A power dissipation
approach is used to model the governing equations of overconstrained
vehicles that move quasi-statically. These equations are shown to be
switched hybrid systems. Standard notions, such as the Lie bracket,
are extended to these switched systems. We then develop a controllability
test for such systems. We explore motion planning primitives in the
context of simplified examples. Another application area is that of
distributed manipulation, where parts are being oriented by a large
array of actuators. Here, too, the issues of discrete behavior as the
part traverses different contact states plays a large role in analyzing
stability. (full report)
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The Bin
Model for Generalization
Alexander Nicholson,
Xubo Song, Yaser
Abu-Mostafa
The problem
of overfitting the data is attacked by using the Bin Model analysis.
This provides a method of bounding generalization error without sacrificing
valuable training data. (full
report)
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Learning
in Hardware
Alexander Nicholson,
Arrigo Benedetti, Yaser
Abu-Mostafa, Pietro Perona
We investigate
the use of learning and adaptation for digital hardware design. We use
reconfigurable hardware devices and discrete optimization methods to
learn circuits from a set of examples. We have shown that this approach
works well for the design of small arithmetic circuits and that significant
performance improvements may be achieved by moving away from a strictly
evolvable (genetic algorithms) approach. (full
report)
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Little
Piece of Cortex
George Panotopoulos, Demetri
Psaltis, Pietro Perona
We introduce
a model of the V1 cortex. This model is composed by an initial filter
stage and two interaction stages, inspired by their biological counterparts.
The model produces results matching the ones obtained by physiological
experiments. (full report)
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Hand
Gesture Biometrics
George Panotopoulos, Demetri
Psaltis
We introduce
a biometric measure based on hand gestures. We use simple filters to
extract features from a gesture captured in the form of still frames.
We then use PCA to perform classification using these features. For
small databases we obtain 100% correct classification. (full
report)
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Divide
and Conquer Strategy for Recognition
George Panotopoulos, Demetri
Psaltis
We devised
a classification strategy based on the division of a single complex
question to more, simpler questions. We showed that this strategy corresponds
to a tree structure and can be implemented by reconfigurable computers.
We demonstrated the efficiency of this strategy on the problem of classification
of handwritten digits. We derived analytical expressions linking the
performance of the overall classifier to the performance of its parts.
(full report)
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A CMOS
Imager with Focal-Plane Computation for Feature Detection
Alberto Pesavento
and Christof Koch
We designed
and tested the first CMOS imager with analog VLSI focal-plane computation
for feature detection. The chip implements a modified version of the
Tomasi-Kanade algorithm that is suitable for integration in a compact
analog VLSI chip. The chip has an array of 8 by 8 pixels and uses few
microW of power per pixel. (full
report)
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Microbat
Nick Pornsin-Sirirak, Yu-Chong Tai
Collaborators: Hany Nassef (UCLA), Chih-Ming Ho (UCLA), Joel Grasmeyer
(AeroVironment), Matt Keennon (AeroVironment)
Through
the discovery of flapping-wing (unsteady-state) aerodynamics, the world's
first electric-powered palm-sized ornithopter has been successfully
developed and test-flown. This effort is enabled by the use of a new
titanium-alloy MEMS (Micro-Electro-Mechanical Systems) airframe/wing
technology to produce light but robust 3-D wings. Parylene-C is used
as wing membrane. This new wing design results in a 40% wing area reduction
compared to the 1st generation wing. We have built a system that includes
a lightweight NiCd battery and an electrical motor, a gearbox transmission
design of 22:1 gear ratio with 90% efficiency, and a DC-to-DC voltage
converter. Together, it allows us to design a complete system with necessary
components within the weight budget for a successful flight. So far,
the best flight duration obtained by Microbat was 18 seconds. It is
mainly limited by the power source. (full
report)
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Minimal
Data Set Optimal Classification
James R. Psota, Malik
Magdon-Ismail, Yaser Abu-Mostafa
We are
developing classification techniques to detect the nature of a pump
malfunction given pump vibration sensor data. The size of the data set
is very minimal, creating the need for an extremely robust classifier
that incorporates all available information. We investigated several
generalized nearest neighbor and Bayesian classifiers. By incorporating
hints, or information about the problem known independently of the data
set, we show that performance can be significantly improved. (full
report)
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Perception
and 3D Reconstruction of Specular Surfaces
Silvio
Savarese, Pietro Perona
The aim
of our work is to investigate how the human visual system perceives
specular surfaces and which cues can be used to recover the shape of
such class of objects. (full report)
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Toward
Prosthetic Systems Controlled by Parietal Cortex
Krishna Shenoy, Sohaib Kureshi,
Richard Andersen, Shiyan
Cao, Joel W. Burdick
At present
there are no satisfactory treatments or assistive aids for people suffering
from neurological disorders such as stroke, ALS, or spinal cord injuries.
Neuroscientists have taken great strides in the past few decades toward
uncovering basic principles underlying our ability to see and move.
The combination of these discoveries and the revolutionary advances
in computer technology have led to an emerging view that neural prosthetics
--- or electronic interfaces with the brain --- may one day be possible.
This project aims to demonstrate the potential for neural prosthetics
to help patients with upper spinal cord injury, which results in the
loss of arm movements. Andersen and colleagues recently discovered a
cortical area in monkeys and humans that encodes the next intended arm
movement. This area is ideally suited to provide high-level control
signals for guiding real or prosthetic arms. We propose to implant chronic
electrode arrays in this region of monkey cortex and to record neural
activity generated during reaching arm movements. We will process these
neural signals in real-time to construct control signals for guiding
a prosthetic arm. Combining behaving-monkey electrophysiology techniques,
state-of-the-art electrode array technology, and feedback control systems
should provide the foundation on which to build neural prosthetics for
humans. Below we outline our major aims and, in the achievements section,
we describe our progress in the past year. (full
report)
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Monotonicity
Hints in Machine Learning
Joseph Sill, Yaser
Abu-Mostafa
This project
focuses on both practical and theoretical aspects of the monotonicity
constraint in machine learning. Learning methods which enforce monotonicity
in models such as neural networks are being developed. In addition,
the flexibility and expressive power of the class of monotonic binary
output functions are analyzed and quantified from a theoretical perspective.
(full report)
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Detection
of Human Motion in a Cluttered Scene
Yang Song, Xiaolin Feng, Luis Goncalves, Pietro Perona
Detecting
humans in images is a useful application of computer vision. Loose and
textured clothing, occlusion and scene clutter make it a difficult problem
because bottom-up segmentation and grouping do not always work. We address
the problem of detecting humans from their motion pattern in monocular
image sequences; extraneous motions and occlusion may be present. We
assume that we may not rely on segmentation, nor grouping and that the
vision front-end is limited to observing the motion of key points and
textured patches in between pairs of frames. We do not assume that we
are able to track features for more than two frames. Our method is based
on learning an approximate probabilistic model of the joint position
and velocity of different body features. Detection is performed by hypothesis
testing on the maximum a posteriori estimate of the pose and motion
of the body. Our experiments on a dozen of walking sequences indicate
that our algorithm is accurate and efficient. (full
report)
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A 2-D
Change Detection and Postitioning System Analog VLSI
Theron Stanford, Christof
Koch
We are
designing analog CMOS chips which will extract information about moving
objects such as their relative size, position, and velocity. We are
using analog circuits because of their high-speed real-time performance.
Immediate applications of this type of chip include electronic security
systems, on- or off-vehicle sensors for intelligent transportation systems
and target detection systems. (full
report)
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Electronic
Nose Project
Samuel Tang,
Rodney Goodman
The proposed
electronic nose chip is composed of four parts: sensor stage, signal
processing stage, database, and classifier. (full
report)
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Swarm
Intelligence and Traffic Safety
Philip
Tsao, Alcherio
Martinoli,
Rodney
M. Goodman
An automotive
controller that complements the driving experience must work to avoid
collisions, enforce a smooth trajectory, and deliver the vehicle to
the intended destination as quickly as possible. Unfortunately, satisfying
these requirements with traditional methods proves intractable at best
and forces us to consider biologically-inspired techniques such as Swarm
Intelligence. A controller is currently being designed in a robot simulation
program with the goal of implementing the system in real hardware to
investigate these biologically-inspired techniques and to validate the
results. (full report)
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Polymer
Based Electrospray Chips for Mass Spectrometry
Xuan-Qi Wang, Amish
Desai, and Yu-Chong Tai
Collaborators: Lawrence Licklider, Terry D. Lee (Beckman Research Institute,
City of Hope Research Center, Duarte, CA)
We have
developed a MEMS system with an overhanging polymer microcapillary 2.5
mm in length and with a 5 µm x 10 µm orifice size at the tip.
The fabricated systems have been successfully interfaced with a mass
spectrometer (MS) to validate electrospray ionization (ESI) for biochemical
analysis. The prediction of a reduction in Taylor cone size has also
been observed with real time ESI fluid visualization from our chip.
Built-in micro particle filters and centimeter long serpentine microchannels
were fabricated on the chip with a low temperature process by using
the Parylene polymer as a structural material, aluminum and photoresist
as sacrificial layers, and bromine triflouride (BrF3)
gas phase etching for final microcapillary releasing. The use of an
overhanging polymer structure adds a new a level of mechanical robustness
that was never achievable with other thin films. Functionality of our
device was proven by consistent detection of Myoglobin in a 200 nM solution
at a flow rate of 35nL/min and a voltage potential of 1.5 kV. (full
report)
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Learning
Object Class Models
Markus Weber, Max
Welling, Robert Fergus, Pietro
Perona
We have
developed a method to automatically learn models of visual object classes
from sets of unlabeled and unsegmented training images. The method has
been demonstrated to work on images of cars and handwritten characters
and it is being adapted to human faces. (full
report)
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Finding
Faces in Cluttered Scenes
Markus Weber, Michael Burl,
Pietro Perona
We have
designed algorithms that learn a probabilistic description of human
faces and other object classes. We have implemented a real-time face
detection system which runs at 1Hz and demonstrates the ability to handle
deformations, occlusions and background clutter. (full
report)
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MEMS
Flow Sensors for Nano-Fluidic Applications
Shuyun Wu, Qiao Lin, Yin Yuen, and Yu-Chong
Tai
We have
developed micromachined thermal sensors for measuring liquid flow rates
in the nanoliter-per-minute range. The sensors use a boron-doped polysilicon
thin-film heater that is embedded in the silicon nitride wall of a microchannel.
The boron doping is chosen to increase the heater's temperature coefficient
of resistance within tolerable noise limits, and the microchannel is
suspended from the substrate to improve thermal isolation. The sensors
have demonstrated a flow rate resolution better than 1 nL/min, as well
as the capability for detecting micro bubbles in the liquid. Heat transfer
simulation has also been performed to explain the sensor operation and
yielded good agreement with experimental data. (full
report)
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Micromachined
Rubber O-ring Micro-Fluidic Couplers
Tze-Jung Yao, Yu-Chong
Tai
The goal
of this project is to develop a "quick-connect" for microfluidic devices.
We have developed a simple silicone-rubber O-ring MEMS coupler. The
MEMS O-ring couplers are easy to fabricate and use, reusable, can withstand
high pressure (>60psi), and provide good seals. To demonstrate this
concept, a quick-connect coupler between a glass capillary tube and
a silicon chip has been fabricated and tested. More than 60 psi seal
has been achieved between a glass tube (860 µm O.D.) and a rubber
O-ring (400µm I.D.) without measurable leakage. (full
report)
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